Typically, a hydrostatic machine has a hydrostatic system which includes an engine, at least one hydraulic pump, and at least one hydraulic motor. The engine drives the hydraulic pump. The hydraulic pump provides hydraulic flow to the hydraulic motor which drives the machine wheels. The hydrostatic machine also has a mechanical brake which is used in addition to the hydrostatic system to stop the hydrostatic machine. The brake is usually spring applied and hydraulically released.
A typical sequence for starting the hydrostatic machine from a stopped position is to first release the mechanical brake, then apply the hydrostatic propulsion system. This sequence prevents the hydrostatic system from "fighting" the mechanical brake which may occur when the hydrostatic propulsion system is driving the wheels or the tracks while the mechanical brake is still engaged.
However, when the hydrostatic machine is located on an incline and is started from a stopped position, the force of gravity acting on the mass of the hydrostatic machine may be greater than the hydraulic pressure currently in the hydrostatic system. When this occurs, the hydrostatic machine may uncontrollably roll down the incline, after the mechanical brake has been released. The hydrostatic machine will continue to roll down the incline until the hydraulic system pressure is sufficient to overcome the force of gravity acting on the mass of the hydrostatic machine.
The present invention is directed to overcoming one or more of the problems as set forth above.